This invention relates to switches, and, more particularly, to a switch having a pendulum or pivot arm movable in response to the application of motion or an inertial force between an open position and a closed position.
Historically, the decorative features of many articles of footwear have involved the use of different accents on the upper or outsole of the shoe such as colors, stripes, cartoon or other characters and other decorations. More recently, and particularly in children""s footwear, the outsole and/or upper of shoes have been decorated with an array of light sources, usually light emitting diodes or LEDs.
In many designs of shoes employing LEDs or other light sources, a light module is mounted in the outsole of the shoe which is connected by wires to LEDs positioned in various locations on the outsole and/or upper of the shoe. As used herein, the term xe2x80x9clight modulexe2x80x9d refers to a self-contained unit consisting of a housing which mounts an electrical circuit including one or more batteries, an integrated circuit (IC) or chip and a switch. The LEDs, in turn, are electrically connected to the IC. Depending on the type of switch employed in the circuit, in response to the application of motion, pressure, an inertial force or some other stimulus to the shoe, the switch is operable to activate the IC, which, in turn, causes the LEDs to turn on and off.
A number of different switches for use in light modules of the type described above have been proposed. The design parameters are quite demanding in that the switch must be small, contain no harmful substances, operate with little or no noise and demonstrate acceptable reliability considering that they are typically activated with nearly every step one takes while the shoe is worn. Mercury switches have been tried, but are not acceptable particularly in shoes for children due to the potential leakage of harmful mercury from the switch. Other switches employ a movable ball to turn on and off, but these have been found to be too noisy and unreliable.
Another switch design in the prior art is a xe2x80x9cspringxe2x80x9d switch such as disclosed, for example, in U.S. Pat. Nos. RE 37,220; 6,525,487; 6,286,975; 6,012,822; 5,969,479; 5,894,201 and 5,812,063. Switches of this type typically include a spring element having one end fixed, and a free end movable with respect to a contact. In response to motion or the application of an inertial force to the light module, such as by movement of the shoe, the free end of the spring element moves from a neutral or open position to a closed position in engagement with the contact. Closing of the switch completes the electrical circuit thus connecting the battery of the light module to the IC allowing it to operate and cause the LEDs to illuminate.
A number of prior patents directed to switches employ the concept of a swinging pendulum operative to open and close the switch. For example, U.S. Pat. No. 6,018,130 teaches a sensor having a permanent magnet located in proximity to a reed switch. A shunt or pendulum swings between a position in which it is located between the magnet and reed switch to block the magnetic field produced by the magnet allowing the reed switch to open. When the shunt moves out of alignment with the magnet and reed switch, the magnetic field produced by the magnet causes the reed switch to close. U.S. Pat. No. 5,450,049 describes a variation of a reed switch-magnet construction, similar to the ""130 Patent design, except that the magnet itself is movable in a swinging or pendulum motion relative to the reed switch.
U.S. Pat. No. 5,794,761 discloses a swinging element consisting of a plate and an elastic rod which are movable between a pair of electrodes located at each end of the range of travel of the swinging element. A control unit adjusts the electrostatic attraction applied to the plate by each electrode so that the switching time of the swinging element is determined primarily by its natural frequency.
U.S. Pat. No. 5,371,662 teaches a pendulum-type switch in the environment of an article of footwear comprising a casing which mounts a first metal contact carried by a conductive block, a second metal contact located along the base of the casing and a swivel device pivotally mounted to the conductive block by a pin. The swivel device includes a pivot arm mounted at one end to the pin and at the opposite end to a counter weight. One lead from a battery connects to the contact, a second lead from the battery connects to a light and the light is also connected by a lead to the second contact. The counter weight is normally held in a neutral position by a torsion spring, but in response to the application of an inertial force the swivel device pivots allowing the counter weight to engage the second contact thus completing the electric circuit and turning on the light.
The switch of this invention is particularly intended for use with articles of footwear as part of a light module including one or more batteries or other sources of power, an IC and wire connections to LEDs or other sources of light. The switch includes a housing having a hollow interior within which a pair of spaced contacts are mounted, at least one of which is connected to the battery. A cover plate is mounted to the housing such that an electrically conductive pivot arm carried by the cover plate is positioned between the spaced contacts. In response to the application of an inertial force to the switch, the pivot arm is movable in the manner of a pendulum into engagement with either one or both of the contacts thus completing the circuit between the battery and IC allowing it to activate the LEDs.
In one presently preferred embodiment, the two contacts are spanned by an electrically conductive plate and one of the contacts is connected to a terminal of the battery. The pivot arm is mounted by a rod, carried by a pair of spaced side plates mounted to the cover plate, in a position to swing between the spaced contacts. A coil spring extends between one of the side plates and the pivot arm which is effective to maintain the pivot arm in a neutral position out of engagement with both of the contacts. In response to the application of motion or an inertial force to the switch, the spring force of the coil spring is overcome allowing the pivot arm to engage one of the contacts. Because a contact is located on either side of the pivot arm, movement of the shoe in essentially any direction causes the IC to be activated resulting in illumination of the LEDs.
In an alternative embodiment, the coil spring is eliminated and the pivot arm is allowed to engage one of the contacts when the shoe is at rest. The IC in this version of the invention is provided with a timer which interrupts the connection between the battery and LEDs after a predetermined period regardless of the position of the pivot arm. Otherwise, the LEDs would be continuously illuminated and the battery would quickly drain. In response to the application of motion or inertial force to the switch of this embodiment, the pivot arm is movable into engagement with the other contact thus effectively resetting the timer of the IC and allowing it to operate the LEDs.